The present invention relates generally to sonic testing apparatus and more specifically to such sonic testing apparatus which is specifically adapted for testing of wooden structural members and in particular wooden utility poles.
Vast numbers of wooden poles are in use today by the utilities in order to support various power transmission and communication wires in elevated relationship to the ground. While generally these wooden poles are subjected to various chemical treatments in order to increase the longevity thereof, they nevertheless are subject to decay which may vary greatly in the rate thereof dependent upon various environmental conditions such as soil composition, moisture, and the like. Accordingly, because of the potential hazards created by an excessively decayed utility pole, the public utilities and others utilizing such poles have found it necessary to develop testing procedures in order to ascertain when the amount of decay present within the pole has reached such a magnitude as to require replacement thereof. Because the cost of purchasing and installing utility poles is relatively high, it is desirable to maximize the useful life of each and every pole. However, because of the widely varying rates of decay which may change dramatically from one pole to the next in the same pole line, it is not possible to merely perform representative testing. Further compounding the difficulty of obtaining reliable and accurate information as to the integrity of the wooden pole is the fact that a majority of the decay which may be present in a given pole will be hidden well within the interior thereof and not be readily discernible from a mere visual inspection thereof. Also, the most prevalent areas for such decay to occur are centered about the ground level contact with the pole. Typically, excessive decay will not occur well below ground level due to the lack of oxygen which is a necessary element for the decomposition of the wood fibers. Similarly, decay will rarely occur much above ground level due to the lack of significant moisture concentrations over extended periods of time as in this area the pole is openly exposed to the drying effects of the surrounding atmosphere.
In developing testing procedures and apparatus for use in conjunction with the testing of such wooden utility poles, it is extremely desirable to provide apparatus which is capable of operating substantially independently of the skill of the operator so as to avoid significant variation in the accuracy of such tests between different operators. Further, it is desirable to provide apparatus which is portable and which may be easily operated with a minimum of pre-test preparation therefor. It is also important because of the area within which most decay of such wooden poles occurs that the test apparatus be capable of covering a relatively large vertical spectrum of the pole in a signle test so as to avoid the necessity of excavating the ground around the pole as well as to avoid the need to conduct successive tests at different elevations thereon. Another important factor for consideration is that a variety of different species of trees may be utilized for such utility poles and these species may very well be intermixed along the same pole line. Thus, it is important that the test apparatus be capable of readily accommodating a wide variety of different wood species which may have different sonic transmission characteristics without the need to invest the time and effort for recalibrating of the test apparatus.
The present invention provides significantly improved sonic testing apparatus which greatly overcomes the difficulties and problems of apparatus heretofore developed. The sonic testing apparatus of the present invention is designed to substantially eliminate the possibility of operator error and may be packaged in such a manner as to render it easily portable. Further, the apparatus is easy and convenient to use and does not require any excavation work to be performed in the vicinity of the pole in order to ascertain the condition of the pole over the entire area of likely decay. Because the apparatus is capable of rendering consistent test results from operator to operator, the number of erroneous or questionable bad pole readings will be greatly reduced thereby significantly decreasing the number of visual boring operations which must be performed. These factors thus all contribute to substantial reduction in the overall costs associated with performing integrity tests on such wooden poles.
It should be noted, however, that while the present disclosure is specifically directed to the use of the present invention in connection with the integrity testing of wooden utility poles, the sonic testing apparatus of the present invention is also well suited for use in non-destructive testing of virtually any wooden structural members such as for example wooden bridge members or the like. Of course, when the testing apparatus is to be utilized in connection with testing of milled timbers or the like, it will be necessary to ascertain the character of the cut resulting in the timber. That is to say, that whether the timber is center cut, quarter-sawn, etc. may very well affect its sonic transmission capabilities and thus necessitate ascertaining the type of cut resulting in formation of the timber. However, given appropriate reference information and test object information, the principals employed in the present invention as utilized in connection with the testing of wooden utility poles is believed to be equally applicable to these other types of structural wooden members.
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.